U.S. patent application number 12/992955 was filed with the patent office on 2011-06-02 for method and circuit for automatic calibration of the power of electromagnetic oven.
Invention is credited to Chen Jinfeng, Li Peng, Shouqing Qiu, Xu Samson.
Application Number | 20110127256 12/992955 |
Document ID | / |
Family ID | 42242315 |
Filed Date | 2011-06-02 |
United States Patent
Application |
20110127256 |
Kind Code |
A1 |
Qiu; Shouqing ; et
al. |
June 2, 2011 |
METHOD AND CIRCUIT FOR AUTOMATIC CALIBRATION OF THE POWER OF
ELECTROMAGNETIC OVEN
Abstract
A method for automatic calibration of the power of
electromagnetic oven includes the following steps: 1) selecting two
current test values within a range of working current of the
electromagnetic oven, making it operate in the case of the current
test values and zero, detecting voltage values of current signals
under the three operation states; calculating, by a CPU, a
coefficient k and an intercept b according to a formula
y.sub.(i)=k.times.i+b using the three sets of data, and storing
them; 2) during operation, calculating, by the CPU, a current
current signal i using a voltage value y.sub.(i) of the current
current signal detected by the current detection and collection
circuit and the coefficient k and intercept b, according to a
formula i=1/k.times.y.sub.(i)-b/k, and in turn calculating a
current power using the current current signal and a current
voltage signal. A calibration program is built in the chip for
setting a parameter and automatically colleting and calculating the
calibration parameter; during operation, the current or power may
be automatically calibrated, which provides an accurate basis for
adjusting the power of electromagnetic oven. The mode in which a
conventional potentiometer is adopted for calibration may be
replaced by the present invention, which results in reduction of
cost and improvement of the reliability.
Inventors: |
Qiu; Shouqing; (Guangdong,
CN) ; Samson; Xu; (Guangdong, CN) ; Peng;
Li; (Guangdong, CN) ; Jinfeng; Chen;
(Guangdong, CN) |
Family ID: |
42242315 |
Appl. No.: |
12/992955 |
Filed: |
December 9, 2009 |
PCT Filed: |
December 9, 2009 |
PCT NO: |
PCT/CN2009/001397 |
371 Date: |
November 16, 2010 |
Current U.S.
Class: |
219/660 |
Current CPC
Class: |
H05B 6/06 20130101; H05B
6/68 20130101 |
Class at
Publication: |
219/660 |
International
Class: |
H05B 6/04 20060101
H05B006/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2008 |
CN |
200810218351.4 |
Claims
1. A method for automatic calibration of the power of
electromagnetic oven comprising: 1) selecting two current test
values i1 and i2 within a range of working current of the
electromagnetic oven, making a main loop operate in turn in the
case of the current test values i1, i2 and zero, detecting voltage
values y.sub.(i 1){grave over ( )} y.sub.(i 2){grave over ( )}
y.sub.(i 0) of current signals under the three operation states by
a current detection and collection circuit; calculating, by a CPU,
a coefficient k and an intercept b according to a formula
y.sub.(i)=k.times.i+b (k.noteq.0) using the three sets of data, and
storing the coefficient k and the intercept b in a memory; 2)
during operation of the electromagnetic oven, calculating, by the
CPU, a current current signal i using a voltage value y.sub.(i) of
the current current signal detected by the current detection and
collection circuit and the coefficient k and intercept b in the
memory, according to a formula i=1/k.times.y.sub.(i)-b/k, and in
turn calculating a current power value using the current current
signal and a current voltage signal detected by a voltage detection
and collection circuit.
2. The method for automatic calibration of the power of
electromagnetic oven according to claim 1, wherein the current
detection and collection circuit comprises a current sampling
circuit, an amplifier and an A/D converter, the amplifier being
connected between the current sampling circuit and an input
terminal of the A/D converter; the voltage detection and collection
circuit comprises a voltage sampling circuit and the A/D converter,
the output of the voltage sampling circuit being connected to
another input terminal of the A/D converter.
3. The method for automatic calibration of the power of
electromagnetic oven according to claim 2, wherein the voltage
sampling circuit comprises diodes D1, D2, resistor divider R17 and
R18 connected between a cathode of the diodes D1 and D2 and the
ground, the anodes of the diodes D1 and D2 are connected to two AC
input lines of the rectifier bridge respectively, the resistor R18
is connected to a capacitor C22 in parallel, and a public end of
the resistor R17 and R18 outputs a voltage signal to the A/D
converter; the current sampling circuit comprises a constantan wire
resistor RK that is connected in series between the rectifier
bridge and the drain of an IGBT and a resistor R8 that is connected
to the constantan wire resistor RK, the output of the current
sampling circuit is connected to an input terminal of the
amplifier, a feedback circuit composed of a resistor and a
capacitor connected in parallel is connected between the input and
output terminals of the amplifier.
4. A circuit for automatic calibration of the power of
electromagnetic oven comprising: a current detection and collection
circuit comprising a current sampling circuit, an amplifier and an
A/D converter, the amplifier being connected between the current
sampling circuit and an input terminal of the A/D converter; a
voltage detection and collection circuit comprising a voltage
sampling circuit and the A/D converter, an output of the voltage
sampling circuit being connected to another input terminal of the
A/D converter; a memory for storing a control program, an operation
program and a current or power calibration parameter; and a CPU of
which an input terminal is connected to an output terminal of the
A/D converter, the memory being connected to the CPU; wherein the
CPU calculates the current or power calibration parameter using a
predetermined current test value and a detected voltage value of a
current signal, stores it in the memory and in turn performs
automatic calibration on current current and current power using
the calibration parameter.
5. The circuit for automatic calibration of the power of
electromagnetic oven according to claim 4, wherein the amplifier,
the A/D converter, the CPU and the memory are integrated in the
same chip.
6. The circuit for automatic calibration of the power of
electromagnetic oven according to claim 4 or 5, wherein the current
sampling circuit comprises a constantan wire resistor RK that is
connected in series between the rectifier bridge and the drain of
an IGBT and a resistor R8 that is connected to the constantan wire
resistor RK, the output of the current sampling circuit is
connected to an input terminal of the amplifier, a feedback circuit
composed of a resistor and a capacitor connected in parallel is
connected between the input and output terminals of the
amplifier.
7. The circuit for automatic calibration of the power of
electromagnetic oven according to claim 6, wherein the voltage
sampling circuit comprises diodes D1, D2, resistor divider R17 and
R18 connected between a cathode of the diodes D1 and D2 and the
ground, the anodes of the diodes D1 and D2 are connected to two AC
input lines of the rectifier bridge respectively, the resistor R18
is connected to a capacitor C22 in parallel, and a public end of
the resistor R17 and R18 outputs a voltage signal to the A/D
converter.
8. The circuit for automatic calibration of the power of
electromagnetic oven according to claim 4 or 5, wherein the voltage
sampling circuit comprises diodes D1, D2, resistor divider R17 and
R18 connected between a cathode of the diodes D1 and D2 and the
ground, the anodes of the diodes D1 and D2 are connected to two AC
input lines of the rectifier bridge respectively, the resistor R18
is connected to a capacitor C22 in parallel, and a public end of
the resistor R17 and R18 outputs a voltage signal to the A/D
converter.
9. The circuit for automatic calibration of the power of
electromagnetic oven according to claim 4 or 5, wherein the memory
is a nonvolatile memory.
10. The circuit for automatic calibration of the power of
electromagnetic oven according to claim 4 or 5, wherein a product
information memory area in the memory stores product information of
the electromagnetic oven.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the electromagnetic oven
technology, and particularly to a method and a calibration circuit
for automatic calibration of the power of electromagnetic oven.
BACKGROUND OF THE INVENTION
[0002] For a general electromagnetic oven, the calculation of the
power of the electromagnetic oven is usually performed by detecting
the current working voltage, the working current and calculating
the current power by a formula power=voltage.times.current.
[0003] The current sampling circuit typically uses an instrument
transformer or a constantan wire resistor to sample the current
small signal, the sampled current small signal is converted into a
voltage signal and then is amplified for calculation. Since a
relatively big error may occur in this manner, according to the
linear expression y=kx+b (k.noteq.0), a potentiometer is to be used
for adjusting, so as to correct the coefficient k in the formula.
Here, a potentiometer is added. During the processes of
transportation and usage, an offset of the resistance value often
occurs on the potentiometer, which leads to a bigger power error of
the electromagnetic oven.
[0004] In addition, the product information of a general
electromagnetic oven usually shows the product model, running
number, production date or bar code information in the manner of a
paster on the machine or packing case, which is easy to be
counterfeited, that is, a name brand may be counterfeited by simple
print paste or packing process.
SUMMARY OF THE INVENTION
[0005] In order to overcome the above mentioned calibration
drawbacks presented in the existing electromagnetic oven
technology, the present invention provides a method for automatic
calibration of the power of electromagnetic oven and a circuit for
performing the same, so as to satisfy the requirements of the
electromagnetic oven with respect to the power calibration,
real-time power calculation and control.
[0006] The method for automatic calibration of the power of
electromagnetic oven according to the present invention includes
the following steps:
[0007] 1) selecting two current test values i1 and i2 within a
range of working current of the electromagnetic oven, making a main
loop operate in turn in the case of the current test values i1, i2
and zero, collecting current signals for each of the three
operation states respectively by a current detection and collection
circuit, and storing output voltage values y.sub.(i 1) y.sub.(i 2)
y.sub.(i 0) of the current detection and collection circuit;
calculating, by a CPU, a coefficient k and an intercept b according
to a formula y.sub.(i)=k.times.i+b(k.noteq.0) using the three sets
of data, and storing the coefficient k and the intercept b in a
memory;
[0008] 2) during operation of the electromagnetic oven,
calculating, by the CPU, a current current signal i using a voltage
value y.sub.(i) of the current current signal detected by the
current detection and collection circuit and the coefficient k and
intercept b in the memory, according to a formula
i=1/k.times.y.sub.(i)-b/k, and in turn calculating a current power
value using the current current signal and a current voltage signal
detected by a voltage detection and collection circuit.
[0009] The circuit for automatic calibration of the power of
electromagnetic oven to realize the above mentioned method
includes:
[0010] a current detection and collection circuit including a
current sampling circuit, an amplifier and an A/D converter, the
amplifier being connected between the current sampling circuit and
an input terminal of the A/D converter;
[0011] a voltage detection and collection circuit including a
voltage sampling circuit and the A/D converter, an output of the
voltage sampling circuit being connected to another input terminal
of the A/D converter;
[0012] a memory for storing a control program, an operation program
and a current or power calibration parameter; and
[0013] a CPU of which an input terminal is connected to an output
terminal of the A/D converter, the memory being connected to the
CPU; wherein the CPU calculates the current or power calibration
parameter using a predetermined current test value and a detected
voltage value of a current signal, stores it in the memory and in
turn performs automatic calibration on current current and current
power using the calibration parameter.
[0014] The amplifier, the A/D converter, the CPU and the memory are
integrated in the same chip.
[0015] In the present invention, a solution for automatic
calculation of the power of electromagnetic oven is proposed
firstly. In this solution, a program module for automatic
calibration of the power is built in the chip. During production of
the electromagnetic oven, the power or current calibration
parameter is automatically colleted and calculated according to a
predetermined parameter, and this calibration parameter is recorded
in a memory built in the chip, the memory having the power off
memory function. During operation of the electromagnetic oven, the
CPU reads the calibration parameter recorded in the memory built in
the chip for performing calibration on the current signal, and in
turn calculates current power value with the voltage signal, which
provides an accurate basis for adjusting and protection of the
power of electromagnetic oven by the CPU.
[0016] The mode in which a conventional hardware potentiometer is
adopted for calibration may be replaced by the present invention,
which results in reduction of cost and improvement of the product
reliability.
[0017] The amplifier, A/D converter, CPU within the circuit for
automatic calibration of the power according to the present
invention are integrated in the same chip, which results in high
chip integrity and simple peripheral application circuit, such that
the difficulty of production and maintenance is greatly
reduced.
[0018] The product information of the electromagnetic oven is
stored in the memory according to the present invention. This
product information may be displayed on the digital tube or LED
through key-press operation, such that the information secrecy
effect is good and the difficulty of counterfeiting products is
greatly increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a block diagram illustrating the principle
according to the present invention;
[0020] FIG. 2 is an embodiment of the circuit diagram thereof.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] The present invention will be described in detail with
reference to the Figures.
[0022] Referring to FIGS. 1 and 2, the illustrated circuit for
automatic calibration of the power of electromagnetic oven mainly
includes: a current detection and collection circuit, a voltage
detection and collection circuit, a memory and a digital logic
control processor CPU, etc.
[0023] The current detection and collection circuit includes a
current sampling circuit, an amplifier and an A/D converter, the
amplifier being connected between the current sampling circuit and
an input terminal of the A/D converter. The current sampling
circuit includes a constantan wire resistor RK that is connected in
series between the rectifier bridge BGI and the drain of the IGBT
and a resistor R8 that is connected to the constantan wire resistor
RK. One terminal of the resistor R8 is connected to an input
terminal of the amplifier (i.e., the 13 Pin of the CHK-S008 chip in
FIG. 2), a feedback circuit composed of a resistor R12 and a
capacitor C7 connected in parallel is connected between the input
and output terminals of the amplifier (i.e., the 13 Pin and the 12
Pin of the CHK-S008 chip in FIG. 2), the input terminal of the
amplifier is connected to a capacitor C8 that is grounded, and the
constantan wire resistor RK1 is connected to a capacitor C5 in
parallel.
[0024] The voltage detection and collection circuit includes a
voltage sampling circuit and the A/D converter. The output of the
voltage sampling circuit is connected to another input terminal of
the A/D converter. The voltage sampling circuit includes diodes D1,
D2, resistor divider R17 and R18 connected between the cathode of
the diodes D1 and D2 and the ground. The anodes of the diodes D1
and D2 are connected to two AC input lines of the above rectifier
bridge BGI respectively, the resistor R18 is connected to a
capacitor C22 in parallel, and the public end of the resistor R17
and R18 outputs a voltage signal to another input terminal of the
A/D converter (i.e., the 7 Pin of the CHK-S008 chip in FIG. 2).
[0025] An input terminal of the digital logic control processor CPU
is connected to the output terminal of the A/D converter, the
memory is connected to a corresponding port of the CPU, and the
memory stores control and operation programs as well as a linear
calibration program of a current amplifier, etc. The memory is a
nonvolatile memory with the power off memory function.
[0026] The above mentioned amplifier, A/D converter, digital logic
control processor CPU and the memory are integrated in a SoC
(System on a Chip) chip, such as a CHK-S008 chip shown in the FIG.
2.
[0027] A current calibration parameter is stored in an area of the
nonvolatile memory in the CHK-S008 chip for calibrating the power
of the electromagnetic oven when a calibration program is executed
by CPU. A product information memory area in the nonvolatile memory
may store the product information of the electromagnetic oven, such
as the information of bar code of the product, manufacturer number,
running number, production date, etc. The product information may
be displayed on the digital tube or LED through key-press operation
so as to enhance the information secrecy effect and greatly
increase the difficulty of counterfeiting products.
[0028] The method for automatic calibration of the power realized
by using the above circuit for automatic calibration of the power
of electromagnetic oven includes the following steps:
[0029] 1) selecting two current test values i1 and i2 within a
range of working current of the electromagnetic oven, making a main
loop operate in turn in the case of the current test values i2 and
zero, collecting current signals for each of the three operation
states respectively by a current detection and collection circuit,
and storing output voltage values y.sub.(i 1){grave over ( )}
y.sub.(i 2){grave over ( )} y.sub.(i 0) of the current detection
and collection circuit;
[0030] calculating, by the CPU, a coefficient k and a voltage value
y.sub.(i 0) corresponding to a case where the current test value is
equal to zero, i.e., an intercept b, according to a formula
y.sub.(i)=k.times.i+b (k.noteq.0) using the two sets of data i1,
y.sub.(i 1) and i2, y.sub.(i 2), and storing the coefficient k and
the intercept b in the memory;
[0031] 2) during operation of the electromagnetic oven,
calculating, by the CPU, a current current signal i using a voltage
value y.sub.(i) of the current current signal detected by the
current detection and collection circuit and the coefficient k and
intercept b in the memory, according to a formula
i=1/k.times.y.sub.(i)-b/k, and in turn calculating a current power
value using the current current signal and a current voltage signal
detected by the voltage detection and collection circuit.
* * * * *